This invention relates to saw blades of the type generally used for cutting wood and other products. Such products may include lumber, layered wood products such as plywood or logs or posts, and non-wood products such as plastic, masonry and nonferrous metals.
The typical construction of a saw blade is a planar piece of metal with an outer cutting edge. The cutting edge typically contains serrations arranged as forwardly inclined teeth. In circular saw blades that operate at very high speeds and with industrial bandsaws, the serrations may have hardened carbide tips.
Saw blades are planar but the serrations and teeth making up the working edge of the saw blade generally protrude to either side of the plane of the blade. This defines the width of the cut of the blade or “kerf.” The cutting action of the teeth produces chips and sawdust. These chips may become lodged in the kerf. It would be more efficient if there were some way to expel the chips as the blade advanced because the presence of chips in the kerf means that the saw is working less efficiently and requires more horsepower.
In addition, as the saw progresses deeper into the cut, more energy is expended. There is more cutting product in the cut and consequently more friction for the saw blade. Friction, in turn, creates heat and possibly vibration. If the workpiece happens to vibrate at the correct frequency, there can even be breakage of carbide saw tooth tips.
Also, depending upon the number of teeth per inch, the pitch of the teeth and their overall size, the actual cut itself may be rough or smooth. In some applications, it is desirable to have a very smooth surface where the cut is made. In general however, in order to have a smooth surface, the teeth must be smaller and more numerous per lineal length, but this choice may require sacrificing both speed and efficiency.
In the past, circular saw blades have been designed which included cutout squares placed along an interior diameter one hundred-eighty degrees apart with inserted carbide tips. This design was an attempt to provide a means for clearing sawdust from the kerf but such designs have proved unsatisfactory.